Introduction: Saturation exposures define border values of parameters describing inert gas de-saturation from human body. There are several operational saturation systems which allow safe decompression of divers, but there is still lack of physiological model which would explain parameters used for calculations using reliable physiological assumptions. In Poland, the system for saturation decompressions has been developed on the basis of the concept of the “extended oxygen window.” According to this model, the first phase of decompression is relatively fast and enhances elimination of inert gas(es) from fast tissues. Then, decompression is slowed down to stabilize gas out flow from the slowest tissue described by the longest tissue half-time (THmax, 180 minutes for helium, 360 minutes for nitrogen, and variable half-time for trimix as depending on content). Material and methods: In the verification phase of the research grant approved by the Ethics Committee, there were 127 man-expositions with young healthy volunteers conducted using air, nitrox, heliox and trimix up to pressures of 11 ATA in the saturation habitat. After at least 48 hours at saturation plateau, pressure was reduced within 1.5 hours by the value of the extended oxygen window (related to inspired oxygen partial pressure). Then decompression was conducted with a rate proportional to inspired oxygen according to the equation: DecoRate = PiO2 x (ln(2) / THmax). Results: There was no symptom of DCS in any decompression conducted according to the presented model (binomial 95 percent CI is from 0.00 to 0.02). Conclusions: Oxygen plays a dominant role in the process of desaturation of inert gas(es) from human body after hyperbaric exposures. It allows fast initial phase of saturation decompression and then controls the rate of further decompression limited by the half-time of inert gas elimination from the slowest compartment. (Supported by the State Committee of Scientific Research Grant 4PO5B09208.)